Simplify for beta launch: single opt-in, GitHub Pages

- Static build at caelum.github.io/hipsters-builders
- BETA badge on landing page
- Simplified Worker: single opt-in, just adds contact to Resend audience
- Removed double opt-in, /confirmar, /alt, welcome email
- Removed @astrojs/node adapter, CNAME (using .github.io for now)
- Audience ID: 1f0625e7-1208-4c1b-8a94-60c2ca2437e8
- Repo made public for GitHub Pages support

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: peas

astro.config.mjs

@@ -4,8 +4,9 @@ import tailwindcss from '@tailwindcss/vite';
 import sitemap from '@astrojs/sitemap';
 
 export default defineConfig({
-  site: 'https://builders.hipsters.tech',
-  server: { port: 5332 },
+  site: 'https://caelum.github.io',
+  base: '/hipsters-builders',
+  server: { port: 3323 },
   output: 'static',
   integrations: [sitemap()],
   vite: {